1. Field of the Invention
This invention relates to a mobile stair system for pets and other small animals, a method of making said mobile stair system, and a method of producing elements of said mobile stair system. Said mobile stair system is most preferably fabricated from rigid or semi-rigid material, including but not limited to rigid polyvinyl chloride (PVC), and is carpeted or covered with some pliable material comprising rubber for use in water. Said mobile stair system may be used by small or handicapped pets (comprising small or handicapped dogs, cats, birds and pigs) or other animals (hereafter referred to in combination as "pets"). The method of making the mobile stair system comprises connecting a number of crossbars between a left side support and a right side support to form a main frame, spreading a covering over the number of crossbars of the main frame, and connecting the number of crossbars, the left side support, the right side support and the covering by using a cord such that the covering serves as a number of stairs. The method of producing elements of a main frame of the mobile stair system comprises using molds in forming said elements, pouring casting material into the molds, allowing the casting material to harden in the mold to form said elements, and removing the precast elements from the mold, i.e. using injection molding.
2. General Background
The present invention relates to a mobile stair system for use by small or handicapped "pets", method of making said mobile stair system, and a method of producing elements of the main frame of said mobile stair system. Said mobile stair system is most preferably fabricated from rigid or semi-rigid material, comprising rigid polyvinyl chloride or heavy cardboard, through which a cord runs and which is carpeted or covered with any kind of pliable material. Light-weight and durable material are used in construction of the mobile stair system to make the mobile stair system easy to carry and long-lasting. In addition, the rigid or semi-rigid material used in fabricating said mobile stair system must be capable of supporting the weight of the "pet" standing or climbing thereon and shall be capable of being readily shaped to a desired configuration.
Currently used portable stairways have a wide variety of applications, applications ranging from construction to hunting. Heavier stairways, usually comprising concrete, are used in construction. Since such stairways often require concrete and are quite heavy, transportation and installation of such stairways are difficult tasks. Manufacturing such stairways is not often an easy task either. Some existing stairways do not provide a required or desired strength. Other stairways are enclosed by a railing to protect injuries due to falls off the side of the stairways. As a result, such stairways often are hard to manufacture, carry, install and use.
In order to simplify the manufacturing, the transportation, the installation and the utilization process of mobile stair systems, the present mobile stair system, the method of making the present mobile stair system and the method of producing elements of the main frame of the mobile stair system are recommended in the present invention.
3. Description of the Prior Art
In the past few years, there have been some improvements in the prior portable stairways, methods of making the same, and methods of producing elements of the same. A few patents have been recently registered which explain different stair systems, stairways, ladders, methods for making the same, and methods of producing elements of the same. Such patents disclose different types of stairways and ladders (comprising concrete stairways and metal ladders), different stair systems, different methods of making some of said stairways, ladders or stair systems, and different methods of producing elements of the same.
Bennett, U.S. Pat. No. 4,995,205, discloses a precast stair system, including a plurality of individually precast steps. The stair system comprises a tread portion and a riser portion, said riser portion being integrally connected to the tread portion and extending generally downward therefrom. One or more stringer elements are precast, independently of the steps, for supporting the steps. The steps are releasably fastened to each stringer element.
Brumbalough, U.S. Pat. No. 4,706,425, discloses a stair unit structure having at least one stair with a riser and a tread fabricated from rigid material such as fiberglass. A reinforcement member coextends along the width of the stair unit structure and is secured at each inside width by a suitable adhesive or any similar material. A flange member is preferably used close to the lowermost riser to secure the stair unit structure to a supporting structure. A turn-down member is preferably used near the rearward edge of the uppermost tread to provide added strength.
Yokomori, U.S. Pat. No. 4,034,525, discloses a construction of step members for building a stairway structure. The construction of each step member comprises a first vertically extending plate-like element provided at one end with a first rolled portion and a second horizontally extending plate-like element provided at one end with a second rolled portion. Fastening means are passed through the openings of the first and second rolled portion to connect the step members to parallel stringers.
Burton, U.S. Pat. No. 3,891,053, discloses a ladder to be mounted on a boat to facilitate a dog climbing into the boat from the water. The ladder comprises an adjustable base member detachably mountable on a supporting structure, a pivot means to be mounted on the base member, a ramp assembly to be pivotally mounted on a pivot pin, a base member including a pair of relatively adjustable base and clamp plates including parallel flanges, and adjustable means mounted on one of said flanges to clamp the base member thereto.
Hanson, U.S. Pat. No. 3,805,464, discloses a precast reinforced concrete integral staircase to be installed as a unit to span the space between two surfaces. The precast staircase is formed of a deep U-shaped elongated beam member with the arm portions of the "U" extending upwardly from the flat base of the "U" defining the stairs, said arm portions providing a supporting structure for the stairs.
Argraves et al., U.S. Pat. No. 3,706,170, discloses a pre-fabricated molded or precast stairway and method of making a prefabricated plastic stairway. In the execution of the invention, the necessary forms are made and into them the desired ingredients are introduced and allowed to set and cure, after which the molded units are removed and used to build the completed stairway. The prefabricated plastic stairway, in addition, has a facing representing brick, stone or other desired ornamental finish.
Each of the above mentioned patents discloses various features of a number of inventions. However, the known prior art suffers certain disadvantages which will be discussed.